1. Field of the Invention
The present invention relates to a method for calibrating yaw rate sensors.
2. Description of the Related Art
Such methods for calibrating yaw rate sensors are generally known. The measuring principle for yaw rate sensors is the use of the Coriolis effect. For that purpose, a seismic mass of the sensor structure is put into a drive oscillation in a drive direction. In the case of an external yaw rate occurring perpendicularly to the direction of the drive oscillation, Coriolis forces occur which cause a detection oscillation into a detection direction of the seismic mass. Imperfections in the mechanical sensor structure may result in cross-couplings of the drive oscillation and the detection oscillation. The cause of this cross-coupling is displacement proportional and is denoted as quadrature.
Process variations in the manufacturing process of yaw rate sensors may disadvantageously result in a variation of the sensitivity of the yaw rate sensors. In conventional methods, the sensitivities of the micromechanical yaw rate sensors are calibrated by applying a yaw rate to each of the yaw rate sensors. Special devices are needed for this purpose, which is disadvantageously associated with a very time-intensive and cost-intensive calibrating method.
An alternative method for calibrating micromechanical inertial sensors, in particular yaw rate sensors, is known, for example, from US Patent Application Publication No. 2011/0167891, according to which the sensitivity of an inertial sensor is determined based on the resonance frequencies of a primary oscillator and a secondary oscillator as well as the quality of the detection mode. Compared to a calibrating method in which a yaw rate is applied to yaw rate sensors, this method disadvantageously results in a lower calibrating accuracy.